1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to transmission of signals at different power levels.
2. Introduction
A wireless communication network may be deployed over a defined geographical area to provide various types of services (e.g., voice, data, multimedia services, etc.) to users within that geographical area. In a typical implementation, access points (e.g., corresponding to different macro cells) are distributed throughout a network to provide wireless connectivity for access terminals (e.g., cell phones) that are operating within the geographical area served by the network.
As the demand for high-rate and multimedia data services rapidly grows, there lies a challenge to implement efficient and robust communication systems with enhanced performance. To supplement conventional network access points (e.g., macro access points), small-coverage access points may be deployed (e.g., installed in a user's home) to provide more robust indoor wireless coverage or other coverage to mobile units. Such small-coverage access points may be referred to as, for example, femto cells, femto access points, access point base stations, home NodeBs, or home eNodeBs. Typically, such small-coverage base stations are connected to the Internet and the mobile operator's network via DSL or cable.
In general, at a given point in time, an access terminal will be served by a given one of the access points in a network. As the access terminal roams throughout the network, the access terminal may move closer to another access point. Under certain circumstances, the access terminal may then reselect to the other access point (e.g., perform a cell reselection in idle mode from its current serving access point to the other access point). For example, to enable an access terminal to access the services provided by an associated femto cell (e.g., a home femto cell), it may be desirable for the access terminal to reselect from a current serving macro cell to the femto cell as soon as the access terminal enters the coverage area of the femto cell.
Accordingly, there is a need for techniques to ensure that an access terminal is able to discover a femto cell when the access terminal is in the vicinity the femto cell. Moreover, it is desirable to achieve discovery relatively quickly and reliably and without significantly interfering with the service provided by other access points operating in the area.